Effects of harvesting on genetic diversity in old growth eastern white pine in Ontario, Canada
Effects of harvesting on genetic diversity in old growth eastern white pine in Ontario, Canada
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DOI：
10.1046/j.1523-1739.1997.96074.x
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发表时间：
1997-06-01
影响因子：
6.3
通讯作者：
Dancik, BP
中科院分区：
文献类型：
--
作者：
Buchert, GP;Rajora, OP;Dancik, BP
对东部白松（Pinus strobus L.）两个相邻的原始老（近似250年生）林分采前和采后基因库中编码16种酶的54个同工酶位点的遗传多样性进行了比较。位于安大略中部的加洛韦湖老松树区。林分之间遗传多样性变化的同时发生表明，由于采伐，这些基因库中发生了真实的和可重复的遗传侵蚀。在每一个立场检测到的等位基因的总数和平均数减少约25%后，树木密度减少75%。多态位点的百分比下降了约33%，从收获前的水平。各林分中约有40%的低频（0.25 > p ≥ 0.01）等位基因和80%的稀有（p < 0.01）等位基因因采伐而丢失。假设的多位点配子多样性减少了约40%，在每个站收获后。每个林分的潜在遗传潜力降低了约50%，这表明这些基因库适应不断变化的环境条件的能力可能已经受到损害。杂合性估计在采后的立场并没有反映减少等位基因丰富度由于收获。观察到的杂合性增加了12%，在一个立场收获后，即使其他遗传多样性措施下降。基因频率的变化，由于收获意味着基因库的自然再生后代的立场可能是很大的不同，从原来的父母。造林做法应确保在再生林分中重新建立剩余原始古老林分的基因库。
Genetic diversity measures at 54 isozyme loci coding for 16 enzymes in megagametophytes were compared between preharvest and postharvest gene pools of two adjacent virgin, old-growth (similar to 250 years) stands of eastern white pine (Pinus strobus L.) in the Galloway Lake Old Pine Area of central Ontario. The concurrence of genetic diversity changes between the stands suggests that real and repeatable genetic erosion occurred in these gene pools as a result of harvesting. The total and mean number of alleles detected in each stand were reduced by approximately 25% after tree density reduction of 75%. The percentage of polymorphic loci dropped by about 33% from preharvest levels. About 40% of the low frequency (0.25 > p greater than or equal to 0.01) alleles and 80% of the rare (p < 0.01) alleles were lost from each stand because of harvesting. Hypothetical multilocus gametic diversity was reduced by about 40% in each stand after harvesting. Latent genetic potential of each stand was reduced by about 50%, suggesting that the ability of these gene pools to adapt to changing environmental conditions may have been compromised. Heterozygosity estimates in the postharvest stands did not reflect reductions in allelic richness due to harvesting. Observed heterozygosity increased by 12% in one stand after harvesting, even though other genetic diversity measures decreased. Gene frequency changes due to harvesting imply that gene pools of naturally regenerated progeny stands may be quite different from the original parental stands. Silvicultural practices should ensure that the gene pools of remaining pristine old-growth stands have been reconstituted in the regenerating stands.